THE RIDDLED CHAIN

Chance, Coincidence and Chaos in Human Evolution

Add “culture” to the alliterative subtitle and “clever” to describe the approach of the author, for this is indeed an intelligent and provocative account of human evolution.

McKee (Anthropology/Ohio State) is a theorist as well as a field paleoanthropologist. He has worked on digs at the storied sites in South Africa (Magapansgat and Taung) where Raymond Dart discovered a famous fossil of a child hominid, not an ape, estimated to be about 2.5 million years old. The structure of the skull provided McKee with a starting-point for his thesis: there is chaos in the world, he claims, because a change in some initial circumstance in our evolutionary history—one that occurred by chance (gene mutation)—has had epoch-making and unpredictable repercussions. The Taung child was a small-brained, large-faced biped. In the process of adapting to standing and walking, McKee speculates, the spinal cord attached to the brain moved centrally so that the head would eventually sit squarely over the spinal column and face forward. These genetic and morphological events, along with evidence from other fossil finds and computer simulations, led McKee to conclude that evolution is self-catalytic (i.e., self-driven). It is the product of change, coincidence, and chaos, climaxing in human evolution with culture, that has increased our adaptability. McKee discredits the popular theory that a climatic cooling led to a loss of forest and the growth of savannahs, thereby driving our ancestors to bipedalism. He also includes a wonderful chapter cataloguing the compromises in anatomy and physiology our species lives with, and he speculates that we are preserving maladaptive traits because of our medical ingenuity.

McKee’s wonderfully rich and thought-provoking text, told with style and winning flashes of humor, is a refreshing entry into the always contentious and endlessly fascinating story of human origins.